Azo dye duplicating process



Patented Apr. 14, 1953 AZO DYE DUPLICATING PROCESS Robert J. Klimkowski,

Florence, Park Ridge, 111.,

Chicago, and Robert T.

assignors to A. B.

Dick Company, Niles, 111., a corporation of Illinois No Drawing.

Serial No. 287,616.

8 Claims.

This invention relates to a process for the reproduction of multiplecopies and it relates more particularly to the reproduction of copies bya new and improved spirit duplicating system. This application is adivision of our copending application Ser. No. 287,616, filed May 13,1952.

To the present, reproduction processes of the type described have beeneffected by systemsgenerally referred to in the art as the gelatinsystem and as the spirit duplicating system. In the gelatin system, amaster sheet is imaged by typing, writing or drawing with an inkcomposition containing a water soluble dye, usually crys- Originalapplication May 13, 1952,

Divided and this application July '7, 1952, Serial No. 297,568

tal violet. The image is transferred in reverse by absorption duringcontact into a gelatin compound disposed in a pan or on the surface of atransfer sheet which then forms the printing medium. The water solubledyestuff transfers from the moist printing medium to form copy uponcontact with impression medium.

In the spirit duplicating system, the image is formed in reverse on amaster by transfer from a carbon type sheet coated with a compositioncontaining a high proportion of a water soluble dye such as crystalviolet, Victoria green, Victoria blue and the like. The image transfersing the building in which it is being used becomes contaminated withfine particles of the dyestufi whereby the personnel within thebuildings and the territory surrounding the buildings acquire a purplishtint which is difficult to remove. I

Because of the highly water soluble nature of. the dyestufl", moistureon the hands of the operator is suflicient to remove substantialquantities of the dye onto the hands whereby it invariably spreads toother parts of the body and clothing. It is diflicult to operate ahectograph system embodying such dyestuffs without staining ones handsand clothing. I

The limitations with respect to the use of dyestuffs highly soluble inwater and in spirit solvents has to the present limited color of copyreproduced to the dye colors formed of such compositions as crystalviolet, rhodamine (red), Victoria blue or Victoria green. It isimpossible to produce intense black copy or copy in any other color thanthe four defined or shades thereof. Attempts have been made to formulatea black by combining the various usable dyestuffs but the best that suchcombinations have been able to produce is gray copy and the differencesin solubility of the various dyes causes differential from the master tocopy sheets, the surfaces of which have been wetted with an alcohol oralcohol and water combination upon contact, as between a compressioncylinder and a printing plate mounted in a rotary duplicating machine.The highly volatile solvents permit the production of a larger number ofcopies and provide for more rapid drying of the copy sheet to reducesetoff and smear. In the spirit duplicating systems, the dyestuff ispreferably contained in a coating such as in a carbon sheet for transferin mirror image onto the printing master by the application of force orthe like.

While hectograph systems of the type described are desirable because oftheir flexibility in use and simplicity in operation for the productionof multiple copies in a rapid and economical manner, there are a numberof serious objections which characterize the process as it is presentlybeing practiced. Most of the objectionable characteristics stem from thehighly dispersible fine particles characteristic of the dyestuffs andthe highly soluble nature thereof in aqueous medium. The fine particlesize of the dyestuff leads to objections in their use for themanufacture of the carbon transfer sheet or inking ribbon. In mostmanufacturing processes, the atmosphere within the formulating andcoating room and the atmosphere for miles surround:

leaching and gradual toning off of one color relative the other toproduce copy of variable color quality from start to finish.

Important also is the ,inabilityto produce permanent copy because of theinstability of the water soluble basic dyes especially upon exposure tolight.

Finally it is difficult to control the solvency of the dye or the effectof the medium in which it is contained with suflicient regularity toproduce copy of uniform quality and often the number of copies ofreadable quality vary from time to time depending upon the conditionsexisting during reproduction.

It is an object of this invention to provide a hectograph system whichis substantially free of the objectionable features of the prior artprocesses of the types described.

Another object is to provide a spirit duplicating system free ofcompounds capable'of coloring or dirtying ones hands, clothing, theatmosphere or the environment during the manufacture and use of theelements employed.

A further object is to provide a spirit duplicating system in whichpermanent copy of good quality is produced.

, A still further object is to provide a new and improved spiritduplicating process including compositions and elements used therein.

Another object is to provide a spirit duplicating system in which thecolor of the copy can be varied over a fairly wide range and includesthe production of intense black copy of good quality.

A further object is-to provide aspirit duplicat-v ing system wherein thecopy is formed of a water and alcohol insoluble coloring compoundincapable of removal, smearing or smudging even under high humidityconditions. 1

A still further object is to provide a new and improved hectographduplicating system capable of producing copy of various color from'asingle prepared master. i

More specifically, it is an object of this invention to provide a newand improved spirit duplicating system and materials for" use inv samewherein the materials involved in themanufacture and use are incapableof transferring color and wherein the copy is developed in the copysheetitself thereby to permit the production of copy with insolubledyes tuffsincapable of use in systems heretofore employed and which aresufficiently stable and insoluble'to remain permanently in the copysheet. Briefly described, instead of forming the image on the master ofa basic aniline dye highly solublein water or spirit solvents, as inprocesses heretofore employed in gelatin or in'spirit duplieatingsystems, the image herein, preferably in reverse, is formed on themaster of a water or alcohol soluble component of a water insoluble dyeand which has no objectionable color transfer value in the state inwhich it exists in the master or in the ink composition, inkingribbon orcarbon sheet with which the master is formed but which upon transfer 'tothe copy sheet forms awater insoluble dye by chemical reaction withother dye formin components contained in nonreactive state in the imagedmaster, or contained in the fluid with which the copy sheet is wettedfor effecting transfer of the imaging component uponcontact, or in thecopy sheet or contained in a fluid-applied to the copy sheet subsequentto transfer 'of'the imaging material from the master. The concepts ofthis inventionare'ca'pable of'a number of modifications which willhereinafter bedescri-bed ingreater detail and for purposes "ofillustration, but not of limitation, examples will now be given of onemode for carrying out the inventive concepts embodied herein.

Example 1 A carbon type transfer sheet is formedfby coatingja; thinfibrous sheet with a composition cornpounded of the following materials:

8 parts by weight carnauba wax 11 parts by weight oxidized 'microwax(Cardis 262) a 3 parts by weight polybutene (Oronite 128) 6 parts byWeight'petrolatum 17 parts by weight mineraloil (100 seconds) 55-partsby weight paradiaz'o diethyl aniline zinc chloride The composition isreduced to molten state ata temperature of about 80 -85 C. forapplicationas a'hot inelt onto the surface of the base sheetinconcentrations ranging from -20 pounds per 3000 square feet.

Example 2 For preparation of the imaged master, the coatedj sheetmanufactured in accordance with Example 1 is positioned withthe coatedside infsurfa'ce contact with'the prepared'su-rface eta-suitable mastersheet whereby material is displaced from the coating to the surface ofthe master to form the mirror image of forces applied against theuncoated side of the coated sheet as by a stylus, writing pen or pencil,typewriter key, die impression or the like.

To the present, the active ingredient in the coating composition fordevelopment of the image in the copy sheet comprises the paradiazodiethyl aniline Zinc chloride which is a Water and alcohol solublecomponent of an azo dye and which has no objectionable color transfervalue thereby to provide for a cleanprocess in the manufacture of thecoated sheet and the imaged master. In the event that it is desirable tointroduce some color for-inspection of the'imaged master, it is possibleto compound the coating composition or the imaging composition with aminute amount of some coloring component selected of any one of the 0.5percent phloroglucin'ol 5.0 percent b-naphthol 2.0 percentdiethanolamine 92.5 percent methanol As the wetted surface of the copysheet moves into surface contact with the imaged master between theimpression roller and the .cylinder mounting the'm'aster, some'ofthe'diazo dye forming component is dissolved from the surface portion ofthe image whereupon coupling takes place between the phloroglucinol andthe p-diazo diethyl aniline zinc chloride at pI-Ilevels adjusted bythedietha'nolamine' tofor'm a water insoluble and'p'e'r'manent deeppurple diazodyestuff in 'direct'image in the copy sheet.

It 'will besignificant thatth'e dyestuif is formed only in the copysheet 'when iti's obser'vedtha-t upon emergence of the cop sheet frombetween the impression 'roller an'd master cylinder very faintif anycopy is visible. Color development rather quickly takes'place once thedye componenta'nd coupler havebeen combined in the'co'py sheet in thepresence of the alkaline medium to form the dyestufif. The copy sheet'iscapable of beingjhandled almost immediately without fear of setoff orsmear and the color produced is permanent in character. I i

The number of copiessecured depends greatly upon the thickness of thecoating of which the image is formed, the amount 'of dye formingc'ompgnent contained in the coating composition and the character andquantity of solvent 7 applied to the copy sheet for effecting transferof the dye component from the imaged master for coupling reaction todevelop color.

, It will be apparent, however, that the intensity of color capable "ofbeing developed by azo dye'system's of the type described permits theproduction of readable, copy with minimum concentration "of dye formingcomponent withthe-result that'by proper'co'n'trol, up to to 500 :gpie'smay "easilybe "secured" from a single masr V V,

copy instead It is believed that the amount of spirit solvent present onthe copy sheet during contact with the master is sufficient to causetransfer of an infinitesimal proportion of the azo dye forming componentpresent and that a minute portion of the carrier or wax base in whichthe dye component is contained is also removed to the copy sheet,otherwise the dye forming component in the master sheet would beconverted into a water insoluble dyestuff incapable of being transferredto form copy in accordance with the concepts of this invention. In thisrespect, the invention herein differs basically from the gelatin or thespirit processes which have heretofore been employed in the reproductionof copy.

Example 4 in the event that it is desired to produce red of purple fromthe master prepared in accordance with Example 2, the copy sheet iswetted with a solution formulated of the following:

5.0 percent phenylmethyl pyrazolone 2.0 percent diethanolamine 93.0percent methanol Example 5 For the production of blue copy from themaster prepared in accordance with Example 2, the

copy sheet may be wetted in conventional manner with the followingcomposition:

5.0 percent 2,3-dihydroxy naphthalene, 6, sulfonic acid 8.0 percentdiethanolamine 10.0 percent water 77.0 percent methanol Example 6 By wayof a still further example, a suitable transfer sheet or a suitableimaging composition in aqueous dispersion or solvent solution for use inthe practice of this invention may be compounded of the followingcomposition:

8.5 percent carnauba wax 14.0 percent oxidized microcrystalline wax 12.0percent dark petrolatum 15.5 percent mineral oil (100 seconds viscosity)50.0 percent paradiazo-ethyl-hydroxy ethylaniline zinc chloride In thepreparation of a transfer sheet, coatings having a weight of about 20pounds per 3000 square feet of surface area are made from a hot meltonto a suitable base sheet by conventional coating technique, such as bya roller coater,

knife coater, spray coater, dip-squeeze process I or the like. Thecoating composition is incapable of free flow when cooled to roomconditions but is capable of transfer responsive to applied force fromthe opposite side of the base sheet to form the mirror image on thesurface of a suitable master sheet positioned in surface contacttherewith.

6 Example '7 Dark purple copy may be produced from the master sheetimaged in accordance with Example 6 by use of a fluid corresponding tothe composition of Example 3 for wetting out the surface of the copysheet in advance of contact with the master. As many as 100 to 500copies can be made before the dye forming diazo component is exhaustedfrom the imaged master sheet. Red copy can be produced by use of thefluid of Example 4 for wetting out the surface of the copy sheet and thesame master can be used to produce blue copy when the copy sheets arewetted with a fluid of Example 5.

The composition of the base in which the diazo dye forming component isembodied in the manufacture of a coated carbon sheet is unimportant andother conventional compositions used in the manufacture of coatedcarbons may be used. Generally such compositions are formulated of waxymaterials in various combinations including carnauba wax,microcrystalline wax, parafiin wax, ozokerite and the like, alone or incombination with softening agents such as mineral oils, fatty acids andthe like. Modification to improve strength and film formingcharacteristics may include the addition of small amounts ofpolyethylene, polybutylene and other polymeric compounds formed ofunsaturated aliphatics and other materials capable of compatability withthe Waxy substances to form a stable composition. The composition of thebase in which the dye component is contained should provide for acontinuous layer capable of transfer to surfaces in contact therewithupon impression but it is preferred to formulate the composition ofmaterials which have slight solubility in the spirit solvents so ascontinuously to cleanse the surface of the imaged master duringproduction of copy.

While it is preferred to apply the carbon type coating composition as ahot melt in the manner described in Examples 1 and 6, it is possible toachieve the desired coating of the base sheet by application of thematerials tions or aqueous emulsions. However more than one coating willusually be required to achieve the desired coating weights on the basesheet. For example, the compositions of Example 1 or 6 may be dissolvedin ethyl acetate, trichloroethylene and the like alone or in combinationwith toluene or benzene diluents to form a 20-40 percent solution or thecompositions of the type described may be dispersed in aqueous mediumwith a small amount of surface active agent to form a 40-60 percentaqueous emulsion. From the solvent solution of lower solids content morethan one coating will be necessary to achieve the desired coating weightbut generally one, or at most two coatings will be sufiicient whencoatings are prepared by the high solids content dispersions of the typedescribed. Where high temperatures are not used to eliminate thediluents, almost any stable diazo dye forming component may be used, butwhere temperatures in excess of C. are used for drying, the diazocomponent is limited because the great majority are unstable at suchtemperature levels.

It is desirable to embody as high concentration of the dye component aspossible in the carbon coating consistent with the ability of thecoating to maintain the desired film characteristics and strength.Generally the amount of the dye forming component introduced as an in-'from solvent solua'cege'n the ability to maintain sufiicient fluidityunder 1 the condition of coating to achieve the desired application andcoverage. For the production of a number of. copies of sufiicientintensity, it is advisable to maintain the concentration of dyecomponent in. excess: of 2.0 percent by weight and preferably in" excessof 50 percent by weight. In general, fluidity of the desired characterfalls offi when the concentration reaches '75 percent by weight but moremay be used with the introduction of fluidizin'g' agents.

With reference particularly to the preferred diazo dye forming system.heretofore described, it has been found that very few dye components arecapable of use in the manufacture of a transfer sheet by coating with ahot melt. To the present, use has-been limited to diazo compounds of thetype described characterized by the formula R1 ti N=NCl wherein the egroup comprises ozHs OH; /C2H5 CzHa C2H5 CH3 02114011 CH3 and I NH.

Compounds capable of use as couplers with the diazo dye formingcomponents in accordance with the practice of this invention are limitedin character. In general, suchcouplers should be capable of removal of ahydrogen ion for com bination with the chloride ion of the diazocompound :for dye formation. Such compounds are limited to aromatics inthe form of amines, such as aniline and substituted anilines likedimethyl aniline, phenolic compounds such as phenol,

resorcinol', phlorogl-ueinol, 2,3,-dihydroxy naphth'al'ene,6-,sulf'onicacid or water soluble salts thereof. and the like, thiocompounds such as 8 thi'o-barbituric acid and cyano compounds such ascyanoacetamide. When the coupler is embodied in the fluid or as acomponent in the copy sheet, as will hereinafter be illustrated, it isdesirable that the coupler be stable and, incapable of developingbackground color because of the pres-- ence thereof over the entiresurface of the copy sheet. It is also desirable to make use of a couplerwhich is readily available and inexpensive. Where the coupler iscombined as a component of the carbon sheet or imaging composition, suchlimitations as to color development and cost are minimized.

For coupling to form the dye by reaction between the coupling agent andthe diazo dye forming component in the copy sheet, it is necessary toprovide for a pH in excess of 3.5 and preferably a pH above 7. Bymaintaining a pH less than 3.5 and preferably as low as 1.5, as byacidification with boric acid, tartaric acid, citric acid and acid saltssuch. as aluminum sulphate or zinc chloride, coupling can be preventedthereby to permit the diazo dye forming component and the coupler to bearranged in the same composition without dye formation but with meansfor adjusting the pH above 3.5 upon transfer to the copy sheet forcoupling to form the colored diazo dyestufi".

Compounds preferably dissolved in the fluid for adjusting the pH to alevel for coupling may include the organic amines such as described inExamples 3-5, amongst others including mono ethanol amine, triethanolamine and other organic amines, ammonium hydroxide, ammonia gas, orinorganic bases'such as sodium hydroxide, potassium hydroxide, zinchydroxide or other Water soluble hydroxides or salts formed of strongbases and weak acids.

By way of further illustration, the following compositions may be usedfor preparing a carbon sheet or imaging composition containing the diazodye forming component for coupling on the copy sheet to develop thevisible image:

Example 8 19.0 percent carnauba wax 25.0 percent cetyl alcohol 14.0percent mineral 011- 42.0 percent p-diazo diethyl toluidine zinc saltThe following are further illustrations of fluid compositions containinga coupler and base substance for adjusting the pH above the level toeffect dye formationiri the copy sheet:

Example 10 3.0 percent phloroglucinol 2.0 percent resorcinol 1.0 percentsodium hydroxide 94.0 percent ethyl alcohol Example 11 5.0 percent2,3-dihydroxy naphthalene, s-sulfonic acid sodium salt 0.8 percentsodium hydroxide 942 percent methyl alcohol While it is most economicalto place the expensive diazo dye forming component in-the ear A coatingcomposition for the preparation of a transfer sheet may be formulated ofthe following:

8.5 percent carnauba wax 14.0 percent oxidized micro wax 12.0 percentpetrolatum 15.5 percent mineral oil 50.0 percent phloroglucinolApplication onto a suitable base sheet may be made in weights of about20 pounds per 3000 square feet from a hot melt raised to a temperatureof about 80-90 C.

When the coating composition is formulated to contain the coupler asdescribed in Example 12, the fluid for wetting out the copy sheet forpurposes of extracting a proportion of the phloroglucinol from theimaged master whereby the dyestuff is developed by reaction in the copysheet may be formulated of the following:

Example 13 2.0 percent ammonium hydroxide 98.0 percent methanol Inoperation of the process, the copy sheet is. adapted to have beentreated to contain a diazo dye intermediate such as p-diazo benzylaniline sulfonate for reaction with the coupler transferred from theimaged master.

By way of further modification, the coupler. and the alkali may becompounded in the carbon sheet and the diazo dye forming componentplaced in the fluid, as illustrated by the following examples:

Example 1a! Carbon coating composition:

5.0 percent carnauba wax- 20.0 percent micro wax 15.0 percent parafiinwax 15.0 percent petrolatum 35.0 percent phloroglucino'l 10.0 percenttriethanol amine Example 15 Fluid containing the diazo componentz 2.0percent p-diazo diethyl aniline zinc chloride 98.0 percent methanol Thecombination described maybe processed in the usual manner for spiritduplication to :form a dark purple water insoluble dye in the imagedareas of the copy sheet, When the diazo component is provided as aningredient in the fluid or as a component of the copy sheet intro duced,as by impregnation, it is imperative that the dye intermediate berelatively free of color and sufliciently stable to prevent thedevelopment of background color in the copy sheet.

By way of still further modification, it is possible in accordance withthe practice of this invention to place both the'd-ia'zo intermediate"andthe coupler in the coating composition thereby to conserve on theamounts thereof employed'in' the preparation of copy. Under such circumstances, the fluid is formulated to containfthe solvent for transfer ofthe colorless materials from the imaged master and also to contain thealkali for adjusting the pH to the level where coupling reaction cantake place on thecopy sheet between the components'in the imaged masterto form the insoluble dye on the copysheet. This mode of practice may beillustrated by the following examples:

Example 16 Carbon coating composition:

5.0 percent carnauba wax 20.0 percent micro wax 15.0 percent paraffinwax 20.0 percent petrolatum 20.0 percent p-diazo diethyl aniline zincchloridev 20.0 percent 1,amino-3,naphthol-4,sulfonic acid.

Example 17 Fluid composition: A fluid for use with aiimaged masterprepared with the composition of Example 16 may be formulated of thefollowing:v

2.0 percent potassium hydroxide. 98.0 percent methanol The use of thesecompositions the practice of this inventionproduces blue copy.v

Example 18 Carbon coating composition: 15.0 percent micro wax 1 I 15.0percent paraflin 30.0 percent petrolatum 30.0 percent p-diaz o diethylaniline zinc chloride 10.0 percent ZA-diaminotoluene dihydrochl'of ridevI In the absence of a solvent, the coupler and the diazo intermediate inthe coating composition remain separate sufficiently to prevent couplingreaction to form the color dyestufi. With a composition of the typedescribed fit becomes unnecessary to make use of an alkali to:adiust thepH to the level desired for coupling heretofore described so that thefluid with which the, copy sheets are wetted out toeffect-transfer .ofthe components from the imagedmaster to the copy sheet for developmentof theimage thereon may be composed essentially of pure solvents such asmethanol, ethanol, 1 or combinations thereof. With compositions ofthetypedesc'ribed, a water insoluble permanent clean dye isxformedinthe; imaged areas of the copy sheet.

vAs previously pointed out, the coupler or. the diazo dye formingcompound may be containedin: the carbon coating composition,asillustrated in Examples 1 and 6, or in Example 11, and the coupler foruse withcompositions of the type set forth in Examples 1 and 6 or thediazo compo nent for. use with compositions of. Examplesfll and 12 maybe disposedin the basesheet; but, any event, at least one of thecomponentsfor developing the dye must .be contained in the. imagingmaterial transferred bycarbon or: by typewriter or by writing ink to themaster. When embodied in the base sheet, such dye forming components maybe incorporated by conventional" coating "or impregnating porating thecomponent fiber containing slurry systems or by incorf as; an ingredientin the" from which -:the eo y.

sheet is. formed Under these circums ances and under circumstances wherethe c mp n nt is applied as a part of the fluid over the entire surface.of the copy sheet, it is desirable that the components in combinationwith the alkali be suficiently stable to avoid the development ofbackground color on the copy sheet.

By w y f still iurther modification, it is possible to embody one of thewater or alcohol soluble dye forming components substantially free. oico or in the imaging m terial and then produce copy in the impressionmat rial by first Wettingr t the py sheetwith the solvent or diluent toeffect transfer of some of the dye forming component from the imagedmaster to the copy sheet and subsequently wetting the copy sheet with asecond fluid containing the coupler, in the event thatthe imaginmaterial contains diazo, or else with a diazo intermediate in the eventthat the coupler is embodied as an ngredi nt in the imaging material orelse with a base in the event that the diazo and coupler are applied onefrom the imaged master and the other with the first fluid for transferof material from the mas er to he copy street It will be bvi us fr m.this description that various combinations are possible such as p ac ingthe diazo, the coupler and the alkali in the carbon sheet, masterpapen'fluid or impression paper except that the diazo intermediate andalkali should be placed in separate syst m The concepts of thisinvention may also. e adapted for use in a gelatin process wherein theimaging composition is iornulated of the following:

Example 19 12.5 percent carnauba wax 12.0 percent microcrystalline wax12.0 percent petrolatum 15.5 percent mineral oil 48.0 percent p-diazoethyl hydroxyethyl aniline zinc chloride 7 Example 20 The coatingsolution is formulatedof the following:

3.0 percent phloroglucinol 2.0 percent resorcinol 7 1.0 percent sodiumhydroxide 94.0 percent ethyl alcohol In operation, the master imagedwith the diazo containing composition is placed and impressed on agelatin'bed. When a deposit of the diazo compound is transferred intothe gelatin, the moist master sheet is then removed. Then a. copy sheetpreviously coated with the solution of Example 20 is pressed intosurface contact with V the imaged gelatin bed. Coupling results in thehe water insoluble diazo tion in acid medium for coupling with an-ainineorthe like t'o'form the dyestuff. a a

Enamels 21 Carbon coating composition;

Example 22 Fluid composition:

10 percent N-N-dimethyl aniline in 1 N hydrochloric acid percent ethylalcohol When the nitrite in the imaged master tranra fers to the copysheet wetted with fluid of Ex! ample 22, the sodium nitrite reacts withthe amine in the presence of acid to form a diazo compound which maythen couple with agents of the type previously described or with theamine when present in excess to form the water insoluble dyestuff in thecopy sheet.

It Will be understood that other dye systems, such as the leuco dyesseparable into substantially colorless dye forming components which arewater and alcohol soluble and one of which may be embodied as acomponent in the imaging or carbon coating material to form the imagedmaster and the other in the fluid or in the copy sheet for reaction withthe component in the imaging material may be used to form the dye upontransfer in the copy sheet The following will illustrate the practice ofthis invention with other dye systems:

Example 23 A fluid for use in combination with the above to develop themalachite green dye in the copy sheet may be formulated of thefollowing:

Erample 24 4 percent potassium dichromate 1 percent nitric acid 45percent ethanol 2 50 percent methanol E mple 25 7 Carbon coatingcomposition:

Example 26 1 percent sodium hydroxide 99 percent ethyl alcohol Example27 Carbon coating composition:

33 percent polyethylene glYCQl (MW about 6000) (carboxwax 6000) 33percent p lyethylene glycol (MW a ou 1 00) (Carbowax 1500) 17 percentsodium sulphate (NaiszQs) 17 percent para-phenylenediamine I h fluidcomposition for use 'in wetting a copy Example 28 20 percent aniline 80percent glacial acetic acid It will be further understood that theconcepts of this invention may be practiced by the use of imagingmaterials in the form of typewriter ribbons, writing ink, drawing crayonor the like embodying one or more of the substantially colorless dyeforming components of the type described for preparation of the imagedmaster and that other components for completing the reaction to form thedyestuff may be placed in the fluid or in the copy sheet for reaction todevelop the dyestufl as an incidence to the transfer of the dye formingcomponent from the imaged master to the copy sheet. The composition ofsuch inking materials or crayons may be formulated with a conventionalbase containing the dye forming component in relatively high proportion.

It will be apparent from this description that a completely new andimproved duplicating process is provided herein capable of use inconventional hectograph duplicating machines to produce copy of improvedquality formed of a water insoluble dyestuff. Until the dye is formed inthe copy sheets, the elements involved in the preparation of the masteror in the manufacture of imaging compositions and the elements presentin materials used to produce the imaged master or the imaged masteritself remain wholly free of color transfer value and therefore avoidsone of the most objectionable features of processes which haveheretofore been employed. In addition, black copy or copy of variouscolors unlimited in their range may be produced and such copies ofdifferent colors may be produced from a single master depending upon thecoupling agent employed or the dye components employed.

It will be evident also that the master sheet, being free of color, maybe handled in the normal manner without dirtying ones hands or clothingand that it may be filed away for subsequent use to produce additionalcopies without loss of definition or quality of the copy produced.

As used in the claims, the term hectograph is intended to includegelatin systems and spirit duplicating systems of the types described.

It will be further understood that changes may be made in the details ofcomposition, arrangement and method of use without departing from thespirit of the invention, especially as defined in the following claims.

We claim:

1. The method of producing copy comprising the steps of imaging a masterwith a composition substantially free of any dye color and containing ahigh proportion of a stabilized diazo dye intermediate and a couplerboth of which are soluble in a medium selected from the group consistingof water, alcohol and mixtures thereof capable of reaction with thediazo dye intermediate to form a substantially water insoluble azodyestuff, the imaging composition being maintained at a pH below that atwhich coupling takes place to prevent reaction between the intermediateand the coupler, wetting the surface of a copy sheet with a fluidcontaining a solvent for the diazo dye intermediate and coupler and "14containing a base for adjusting the pH to permit reaction between thediazo dye intermediate and coupler to form the azo dyestuff, contactingthe wetted copy sheet with the imaged surface of the master to effecttransfer of some of the imaging material to the copy sheet wherebyreaction takes place to form the azo dyestuff therein.

2. The method of producing copy by spirit duplication with a masterimaged with a material containing a large proportion of a stabilizedWater and alcohol soluble diazo dye intermediate lacking in colortransfer value and a large proportion of a water or alcohol solublecoupler capable of reaction with the diazo dye intermediate at pH levelsabove 3.5 to form an azo dyestuff, comprising contacting the imagedsurface of the master with a copy sheet wetted with a fluid containing asolvent for the diazo dye intermediate and coupler and containing analkali for adjusting the pH above the level where coupling may takeplace to form the azo dyestuff whereby some of the diazo dyeintermediate and coupler transfers from the imaged areas of the mastersheet to the copy sheet where reaction takes place to form the azodyestuff.

3. The method of producing copy by a duplicating process comprising thesteps of positioning the surface of a duplicating master in contact withthe coated side of a transfer sheet having a transfer coatingsubstantially free of any dye color and containing a water and alcoholsoluble diazo dye intermediate stabilized against reaction in stronglyacidic medium, and a water and alcohol soluble coupler, imaging themaster by transfer of coating from the transfer sheet in response toapplied force, wetting the surface of the copy sheets with a solvent forthe coupler and diazo and a base for adjusting the pH concentration to arange wherein reaction can take place between the diazo and coupler toform the corresponding azo dyestufi, contacting the imaged master withthe wetted side of the copy sheets whereby suflicient of the diazo andcoupler transfer from the imaged areas for reaction to form an azo dyein corresponding areas of the copy sheets.

4. The method of producing copy by a duplicating process comprising thesteps of positioning the surface of .a duplicating master in contactwith the coated side of a transfer sheet having a transfer coatingsubstantially free of any dye color and containing a stabilized waterand alcohol soluble diazo dye intermediate, a water and alcohol solublecoupler and an acidic medium to prevent formation of an azo dyestuiftherebetween, imaging the master by causing transfer of coating from thetransfer sheet in response to applied force, wetting the surface of thecopy sheets with a solution containing a solvent for the coupler anddiazo and a base for raising the pI-I to a range which permits reactionbetween the diazo and coupler to form an azo dyestuff, and contactingthe imaged master with the wetted copy sheets whereby sufiicient of thediazo and coupler transfers from the imaged areas for reaction in thecopy sheets to form an azo dye.

5. The method of producing copy by a duplicating process comprising thesteps of positioning the surface of a duplicating master in contact withthe coated side of a transfer sheet having a transfer coatingsubstantially 'free of any dye color and containing a high concentrationof a coupler and. diazo dye intermediate stabilized against reactionwith the coupler in strongly acidic medium, imaging the master bytransfer of coating from the transfer sheet in response to appliedforce, Wetting the surface of the copy sheets with a solvent for thecoupler and diazo and a base for adjusting the pH concentration to arange Where coupling reaction can take place between the diazo andcoupler to form the corresponding azo dyestufi, contacting the imagedmaster with the wetted side of the copy sheets whereby sufficient of thediazo and coupler transfers from the imaged areas for reaction to forman azo dye in corresponding areas of the copy sheet.

6. The method of producing copy by a duplieating process comprising thesteps of positioning the surface of a duplicating master in contact withthe coated side of a transfer sheet having a transfer coatingsubstantially free of any dye color and containing a high concentrationof a coupler and diazo dye intermediate stabilized against reaction toproduce a dyestufi without adjustment of pH, imaging the master bytransfer of coating from the transfer sheet in response to appliedforce, wetting the surface of the copy sheet with a solvent for'thecoupler and diazo and a compound for adjusting the pH concentration to arange where coupling reaction can take place between the diazo andcoupler to form the corresponding dyestuif, contacting the imaged masterwith the Wetted side of the copy sheets whereby sufi-"icient of thediazo and coupler transfers from the imaged areas for reaction to forman azo dye in corresponding areas of the copy sheets.

7. The method of producing copy by spirit duplication using a masterimaged with a material containing a large proportion of a coupler and adiazo dye intermediate lacking in color transfer value and stabilizedagainst reaction in strongly acidic medium, comprising contacting theimaged surface of the master with copy sheets wetted with a fluidcontaining a solvent for the diazo dye intermediate and coupler and analkali for adjusting the pH above the level where cou- 16 pling reactioncan take place to form the az'c dyestuif whereby some of the diazo dyeintermediate and coupler transfers from the imaged areas of the masterto the copy sheet on contact where reaction takes place to form the azodyestuff.

8. The method of producing copy by spirit duplication with a masterimaged with a composition t inin a large proportion of a coupler anddiazo dye intermediate stabilized against coupling reaction to producean azo dyestuif until adjustment of the pH and both of which are solublein a medium selected from the group consisting of alcohol and watecomprising contacting the imaged surface of the master with a copy sheetwetted with a fluid containing a solvent for the diazo dye intermediateand coupler and a medium for adjustment of the pH to the level wherecoupling reaction between the diazo and the coupler can take place toform the azo dyestufi whereby some of the diazo dye intermediate andcoupler transfers from the imaged areas of the master to the copy'sheetwhere reaction takes place to form the azo dyestuff.

ROBERT J. KLIMKOVVSKI. ROBERT T. FLORENCE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 38,086 Underwood Nov. 31, 1863 831,582 Thorpe 1 Sept. 25, 19061,514,222 Murray Nov. 4, 1924 1,917,370 Hickman July 11, 1933 2,146,976Neidich Feb. 14, 1939 2,202,529 Lengel May 28, 1940 2,289,714 Land July14, 1942 2,364,359 Kienle et a1 Dec. 5, 1944 2,526,995 Clark Oct. 24,1950 2,597,306 Eaton et al May 20, 1952

1. THE METHOD OF PRODUCING COPY COMPRISING THE STEPS OF IMAGING A MASTERWITH A COMPRISING TION SUBSTANTIALLY FREE OF ANY DYE COLOR ANDCONTAINING A HIGH PROPORTION OF A STABILIZED DIAZO DYE INTERMEDIATE ANDA COUPLER BOTH OF WHICH ARE SOLUBLE IN A MEDIUM SELECTED FROM THE GROUPCONSISTING OF WATER, ALCOHOL AND MIXTURES THEREOF CAPABLE OF REACTIONWITH THE DIAZO DYE INTERMEDIATE TO FORM A SUBSTANTIALLY WATER INSOLUBLEAZO DYESTUFF, THE IMAGING COMPOSITION BEING MAINTAINED AT A PH BELOWTHAT AT WHICH COUPLING TAKES PLACE TO PREVENT REACTION BETWEEN THEINTERMEDIATE AND THE COUPLER, WETTING THE SURFACE OF A COPY SHEET WITH AFLUID CONTAINING A SOLVENT FOR THE DIAZO DYE INTERMEDIATE AND COUPLERAND CONTAINING A BASE FOR ADJUSTING THE PH TO PERMIT REACTION BETWEENTHE DIAZO DYE INTERMEDIATE AND COUPLER TO FORM THE AZO DYESTUFF,CONTACTING THE WETTED COPY SHEET WITH THE IMAGED SURFACE OF THE MASTERTO EFFECT TRANSFER OF SOME OF THE IMAGING MATERIAL TO THE COPY SHEETWHEREBY REACTION TAKES PLACE TO FORM THE AZO DYESTUFF THEREIN.